The Primary Research Of Fractal Growth And Population Differentiation On An Invasive Plant Solidago Canadensis

Solidago canadensis L. have been one of the most noxious invasive plants in the Yangtze Delta, China. Many studies on its dynamics of distribution, hazard, invasive mechanism and the like, have been done in past years. The growth law of Solidago canadensis L., however, was ignored by scholars at home and abroad, so was the geographic variation in different habitats and different areas. This paper is to study the fractal growth of Solidago canadensis L. by use the Fractal Theory, and analyse its population trait differentiation in different habitats and different areas by studies in the wilderness or in the common-gardens. It is to provide a theory and a scientific gudiance for control the further spread of Solidago canadensis L..Relevant documents were consulted and field studies were carried out in the north shore of the Hangzhou Bay, and some studies were done in the common-gardens, etc. The main results are summarized as follows:(1) In the field study in Hangzhou, allometric fractal characteristic was presented in the leaf growth of Solidago canadensis L.. Leaf fractal dimension changed with time and reached the max (1.3390) in July. Moreover, the fractal dimensions of the non-arbor were much bigger than the ones of the arbor.(2) The relative height growth rate also reach the max in July. The fractal dimension between height and basal diametre was a dynamic relationship and reduced to 2/3 with the growth of plant However, The fractal dimension between stem dry biomass and basal diametre was invariably 2.68, which was no significant difference to 8/3, compared to its 95% confidence interval.(3) The mass of per thousand seeds was 0.0471±0.0104 g in Hangzhou; Their terminal velocity (Fr) was 0.26±0.07 m/s ,and the relative relieve height {H_rel) was 105.58±3.58 cm.(4) Three different sample sites were investigated, located in Shanghai, Hangzhou and Jianxin respectively. It was found that the common companion plants in wet habitat were some non-invasive plants of Gramineae, like Phragmites australis; the common companion plants in terrestrial habitat are some invasive plants of Compositae, for instance, Conyza canandensis; some shade plants was also found under the tusscok of Solidago canadensis L., such as Duchesnea indica.(5) ANOVA shows that different water regimes had notable efffects on most traits of Solidago canadensis L., whatsoever feild investigation or studies in the common garden. Solidago canadensis L. was much higher and bigger in terrestrial habitats. It exhibited a strong phenotypic plasticity in both wet and terrestrial habitats, with a higher plasticity index in the common-gardens.(6) Significant differences existed in height, leaf biomass, flower biomass and aboveground biomass of Solidago canadensis L. among the three sites. But no difference was discovered in the basal stem diameter, leaf-stem ratio and height ration.Some important conclusions also are summarized here:(1) The leaf area will grow bigger quickly with the increase of the fractal dimension, which enables a much higher rate for carbon fixation. And the fractal dimensions of the non-arbor are much bigger than that of an arbor, indicating that herbaceous invasive plants have an advantage against trees in leaf growth.(2) The formation of a dynamic fractal relationship between above-ground biomass and height is probably due to the fractal between the height and the basal diameter. In addition, the maximum fractal dimension between above-ground biomass and height of Solidago canadensis L. reach 3.5396, bigger than that of Aneurolpidium Chinese, Carex lasiocarpa and Aneurolpidium dasystachys, which implies that the invasive plant is more advantageous against other plants in growth thanks to its capacity of space occupation.(3) A terrestrial habitat is more fit for growth of Solidago canadensis than a wet one. Due to the fact that plant traits are influenced by multiple biotic and abiotic factors, a significant deviation in inflorerscence biomass of Solidago canadensis L. are found in the three sites whereas their climate is resemble, indicating that plants have a different energy allocation for reproduction.